The Objectivist ethics holds that the actor must always be the beneficiary of his action and that man must act for his own rational self-interest. But his right to do so is derived from his nature as man and from the function of moral values in human life—and, therefore, is applicable only in the context of a rational, objectively demonstrated and validated code of moral principles which define and determine his actual self-interest. It is not a license “to do as he pleases” and it is not applicable to the altruists’ image of a “selfish” brute nor to any man motivated by irrational emotions, feelings, urges, wishes or whims.

This is said as a warning against the kind of “Nietzschean egoists” who, in fact, are a product of the altruist morality and represent the other side of the altruist coin: the men who believe that any action, regardless of its nature, is good if it is intended for one’s own benefit. Just as the satisfaction of the irrational desires of others is not a criterion of moral value, neither is the satisfaction of one’s own irrational desires. Morality is not a contest of whims . . . (“Introduction,” The Virtue of Selfishness, ix.)

But how to apply the Protagorean principle to health, so you can egoistically live your own life to its fullest and best? How to apply it, so you can better raise children? How to apply it, so you can provide rational principles of health to friends, so their lives can be better, too?

We have to appeal to the special sciences and evolution, as Dr. Michael Eades does in his blog post "Hard Wired to the Past."

After discussing in his post some quotes from a Scientific American article on cats and a poem about cats by J.R.R. Tolkien, Dr. Eades says:

We, ourselves, like cats, walked “in thought unbowed, proud, where loud roared and fought [our] kin, lean and slim, or deep in den in the East [and] feasted on beasts” in a time long past. And just like fat cats on mats everywhere, we remember, too, those “fierce and free” primal days, if not in our conscious brains, at least in our DNA. We are hardwired to gobble meat with “huge ruthless tooth in gory jaw.” If you don’t believe me, take a look at this YouTube of chimps, our nearest genetic ancestor hunting and eating meat....We’ve developed our large brains and our social instincts as a consequence of meat eating. I’m planning a post on this subject in the near future, so you can see how our very humanness arose because we developed a taste for meat. We are carnivores to our very cores – were we not, we would still be roaming the savannas with brains the size of grapefruits.

We are not, by nature, grain eaters. We were not conditioned and have not evolved to eat grains, table sugar, lots of salt, etc. -- those are practices and recommendations based on desperation (early societies needing to feed lots of people, or die) and a mismeasure of man. We learn this, not by arbitrarily attacking agriculture, capitalism, and human pleasure, but by applying the rigorous, objective methods of science to study man's health and well-being.

We should also be careful to not follow false arguments or premises like 'if it's healthy, it will be harsh and rigidly disciplined' or 'if I eat healthy, I'll be missing out on a lot of things I like.' Eating right -- it may surprise us only if we suffer under false, unchecked premises -- is easy, enjoyable, and pleasant.

You should at least cut back, way back, on your pizza, bread, hamburgers, and candy. True, you give them up, and you are missing them and the pleasure they give. But turn that around. Since you can only eat so much, since we are finite and limited, when you eat candy and pizza and all, you are missing out on eating more beef tenderloin, lobster, goat cheese, cantaloupe, nuts, strawberries, blueberries...none of which attack your body as do candy and flour, which are long-term self-destructive. What's more, pleasure as such is not a value; it needs to be put in context, it needs to be evaluated in terms of human life and cause and effect. Some pleasures are rational, some are not.

If we are to have man -- man qua rational animal, considered across the whole of his life span -- as the standard of value in our lives, we should then eat not as whim dictates, but as our nature dictates. Following our nature, after all, is what makes us successful in life. And it feels good, and it makes us happy.